Automatic door closer and check mechanism



Feb. 26, 1963 AUTOMATIC DOOR CLOSER AND CHECK MECHANISM Filed July 24, 1961 2 Sheets-Sheet 1 13 207 i fi 27 i i/ 2]. i 54,2 ,4/ T l5 57147-717 H INVENTORS 6207a k. MUM/0 firu e 5, B/c/e //77a/7 4TTORA/EY.

Feb. 26, 1963 G. RQMILLARD ETAL 3,078,500

AUTOMATIC DOOR CLOSER AND CHECK MECHANISM Filed July 24, 1961 2 Sheets-Sheet. 2

INVENTORS 620/ e KM/Y/ard /7 Era/ca fifi/oe/man era.

United States Patent 3,078,500 AUTOMATIC DGUR CLOER AND CHECK MECHANEM George R. Millard, Tekonsha, Bruce B. Bidelman, Marshall, and Raymond R. Martin, Alhion, Mich, assignors to Ronan 8: Kunzl, Incorporated, Marshall, Mich.

Filed July 24, 1961, Ser. No. 126,253 11 Claims. (Cl. 16-52) This invention relates to improvements in automatic door closer and check mechanism. The principal objects of this invention are:

First, to provide a novel form of double crank and cam mechanism which can be mounted in a narrow space in the header of a doorway to automatically close and control the motion of a door opened either inwardly or outwardly of the doorway.

Second, to provide a door closer cam and crank assembly which distributes the loads incident to the opening and closing forces between two driving crank pins and cam surfaces thereby increasing the life of the operating mechanism.

Third, to provide a novel form of door operating crank and coacting symmetrical cam surfaces on a spring actuated closer plate which will aiiord door restraining engagement between the crank and cam down to a very narrow angular range of motion when the door is in closed position but which permits easy opening of the door in either direction by disengagement of the crank from the restaining areas of the cam.

Fourth, to provide a novel door actuating crank and coacting cam plate with dual peak in the cam plate for holding the door in open position.

Fifth, to provide a door operating crank and coacting cam plate which minimize the unit pressure developed between the crank and the cam plate and which provides for a maximum longitudinal travel of the cam plate during opening and closing motion of the door so that motion of the cam plate can be effectively regulated by a hydraulic check cylinder.

Sixth, to provide a double acting crank and cam plate for a door operator which permits the door to be opened in either direction, but which can be selectively conditioned to open in only direction and which may further be selectively conditioned to permit or prevent movement of the door to a hold open position in either direction.

Other objects and advantages of the invention will be apparent from a consideration of the following description and claims. The drawings, of which there are two sheets, illustrate a highly practical form of the door operating crank and cam mechanism.

FIG. 1 is a fragmentary side elevational view ofa doorway with a door and the door operating mechanism of the invention mounted therein.

FIG. 2 is a fragmentary end elevational view of the door operating crank taken along the plane of the broken line 22 in FIG. 1, a portion of the door being broken away in cross section.

"FIG. 3 is a bottom plan view of the door operating mechanism shown in FIG. 2 as the same would appear when viewed from the bottom as installed at the top of the doorway with a part of the bottom plate of the mechanism broken away.

FIG. 4 is an elevational view of the door operating crank shown in FIG. 3.

FIG. 5 is a bottom plan view of the driving and regulating cam plate of the door closer with the door operating crank shown in full lines in a position corresponding to the closed position of the door, the bottom of the crank being broken away in cross section.

FIG. 6 is a fragmentary horizontal cross sectional view 3,078,500 Patented Feb. 26, 1963 ice taken along the plane of the line 6-6 in FIG. 2 and looking upwardly as from the bottom of the doorway with the door and door operating crank rotated slightly toward open position.

FIG. 7 is a fragmentary vertical cross sectional view taken along the plane of the line 7-7 in FIG. 3. Attention is directed to the fact that FIG. 7 in inverted due to the bottom plan character of FIG. 3.

FIG. 8 is a fragmentary vertical cross sectional view taken along the plane of the line 8-8 in FIG. 3. This view is also inverted in the sense that the bottom plate in FIG. 8 is actually the top plate in the installed position of the mechanism.

FIG. 9 is a fragmentary vertical cross sectional view taken along the plane of the line 99 in FIG. 6 and again this view is inverted the same as FIGS. 7 and 8.

FIG. 10 is a fragmentary bottom plan view similar to FIG. 3 with the bottom plate removed to illustrate a selective adjustment of the mechanism to block opening motion of the door in one direction.

As is best shown in FIG. 1 the door operating mechanism of the invention is installed in the header 1 of a doorway frame 2 above the door 3. The door closing mechanism is indicated generally at 4 and is provided with a depending door operating pin 5 having a squared or noncircular end 61 supporting and turning with the door 3 as the door is opened and closed. The door operating mechanism 4 includes a reciprocable cam plate which will be described in detail and which is connected to the piston rod 6 of a spring actuated hydraulically retarded cylinder 7 also mounted within the header 1 of the door frame. The hydraulic cylinder 7 provides the spring force for closing the door and hydraulic control of the closing motion transmitted through the piston rod 6, but in as much as a variety of hydraulic check cylinders are well known and useable in connection with the door operating crank and cam no details of the cylinder are illustrated.

As appears most clearly in FIG. 2 the door closer 4 consists of an upper plate 8 and a spaced lower plate 9 secured together in spaced relationship as by the screws 10 with a flat cam plate 11 reciprocally mounted between the top and bottom plates as will be described. At one end the cam plate 11 is connected by the yoke 12 to the previously described piston rod 6 of the door check cylinder 7. The cam plate is guided in its motion between the body plates 8 and 9 by a pair of inner rollers 13 mounted on the inner end of the cam plate toward the cylinder 7 and a pair of outer rollers 14 mounted at the outer end of the cam plate 11. The inner rollers 13 are mounted on the projecting upper and lower ends of pins 15 pressed into holes 16 near the inner end of the cam plate. The rollers 14 are mounted on the upper and lower ends of pins 17 pressed through the holes 18 near the outer end of the plate 11. Y

The rollers 13 and 14 are guided in downwardly facing grooves 19 formed in the bottom of the upper body plate 8 and in upwardly opening grooves 20 formed in the top of the bottom plate 9. Particular attention is directed to FIGS. 6 and 9 which illustrate the inner rollers 13 as having a relatively close fitting engagement within the grooves 19 and 20 while the rear rollers 14 have a relatively loose guided engagement in the same slots as indicated by the clearance between the rollers 14 and sides of the grooves as at 21. The significance of this clearance will be pointed out presently. The cam plate 11 is supported mid-way between the body plates 8 and 9 by the lower rollers of each pair and defines an inner cam opening 22 of irregular but symmetrical contour which will be described in detail presently. Extending through the cam opening 22 is an operating cam 23 having bifurcated arms 24 projecting to opposite sides of a central body portion 25. The previously described hinge pin 5 for driving the door 3 depends from the lower branch of the arms 24 and is fixedly pivoted in the doorway by the ball bearings 26 mounted in the bottom body plate 9 between the grooves 2%. (See FIG. 2.) The upper flange 24 of the bifurcated arms carries a. pin 27 fixedly pivoted in the ball bearing 28 mounted in the upper body plate 3. The central body 25 of the crank spaces the bifurcations of the arms 24 above and below the cam plate 11 and the extremities of the arms 24 carry duplicate and symmetrically arranged crank pins 29 which extend through the cam opening 22 and coact with the edges thereof as will be described.

The action of the crank pins 29 with respect to the edges of the cam opening 22 is best illustrated in FIGS. 5 and 6 from which it will be noted that the cam opening 22 has two symmetrically arranged inwardly opening semi-circular recesses 30 which receive the crank pins 29 in the centered position of the crank 23 and the closed position of the door 3. The relatively close simultaneous engagement of the pins 29 against the inner sides of the recesses 31} as in FIG. 5 prevents unintentional swinging of the crank 23 and holds the door in closed position against wind and air pressure which cause the door to sWing undesirably. The inner or left edges of the recesses 3d join with the forwardly converging symmetrical edges 31 and form retaining peaks 32 at the junction of these edges. A definite force must be applied to the door to cause the pins 29 to move over the peaks 32 in an opening motion. It is here that the clearance 21 between the inner rollers 14 and the grooves 19 and becomes important and attention is invited to FIG. 6 where it will be noted that counterclockwise rotation of the crank and the arms 24 will apply a corresponding counterclockwise twist force to the cam plate 11 causing the upper recess 20 to swing sufficiently to clear the peak 32 from the upper crank pin 29 thus permitting further rotation of the crank with opening motion of the door. This twist of the cam plate 11 is illustrated in exaggerated amount by the overhang 33 of the cam plate over the upper edge of the body plate 8. In actual practice it has been found that by ma king the rear or inner rollers 14 smaller than the outer rollers 13 by about .030 to .035 inch, suflicient tilting or twist motion of the cam plate is achieved to permit the crank pins 29 to fit closely within the recesses 30.

At their inner or right edges the cam recesses merge into inclined driving edges 34- which converge transversely inwardly of the cam plate to spaced hold open peaks 35. As is shown in FIGS. 5 and 6 counterclockwise rotation of the crank 23 causes the lower crank pin 29 to travel upwardly on the drive edge 34 simultaneously moving cam plate 11 to the right and extending the piston rod 6 of the door closer cylinder. The upper crank pin 29 idles generally along the arcuate converging surface 31 until it passes into an auxiliary driving slot 37 having a driving surface 38 terminating in an auxiliary hold open peak 39 and recess 40. The upper crank pin traverses the surface 38 simultaneous with the traversing motion of the lower pin along the lower drive surface 34 thus distributing the opening and closing forces on the coacting cam and pin parts. This lengthens the life of the mechanism.

Since the working edges and peaks of the cam opening 22 are symmetrical about the longitudinal center line of the cam plate 11, the crank 23 can obviously be rotated in either direction by inward or outward opening motion of the door. If the crank pins 29 do not pass over the hold open peaks and 39, the regulated spring pressure of the piston rod 6 acting on the cam plate will draw the cam plate back to the left in which case the surfaces 34 and 38 act to drive the crank pins 22 and impart closing motion to the door. In the event that it is desired to condition the closer mechanism to closed and by reaching upwardly with a screw driver through one of the holes 43, it is possible to rotate the selected pawl 41 into a blocking position at the end of the auxiliary hold open recess 40. The cooperating arm 24- of crank 23 then will not travel far enough to permit pin 29 to move over the auxiliary hold open peak 39 and the door will swing closed as soon as released. Obviously one or both of the pawls 4.1 may be thus adjusted.

Should it become desirable either as a temporary or permanent arrangement to prevent opening motion of the door 3 in either direction, the cam plate 11 is provided with symmetrically located tapped holes 44 adjacent the door centering peaks 32 and these holes are adapted to selectively receive a blocking screw 45 as shown in FIG. it) so that the head of the screw engages the adjacent end of the bifurcated arm 24 on the crank preventing rotation of the crank in one direction. The cam plate and crank would then continue to regulate the opening and closing motion of the door in the manner described but in one direction only.

It will be recognized that the mechanism of the door closer can be installed and actuated in a variety of arrangements including double or single swinging motion of the regulated door and with or without a hold open action at the open position of the door. The regulating mechanism is thus adaptable to a variety of situations and occupies a minimum of space both vertically and transversely within the header of a doorway. The thin character of the closer 4 coupled with the extended linear travel of the cam plate permits the closure to actuate a hydraulic check cylinder of correspondingly small diameter with a maximum of travel. The closure accordingly can be installed in a relatively narrow vertical space within the header of a door and still obtain or provide effective regulation of the closing motion of the door.

What is claimed as new is:

1. In a door closer having a hydraulic cylinder with a spring pressed piston rod reciprocable therefrom, mechanism for operatively connecting said rod to an oppositely swingable swinging door comprising,

a pair of mounting plates secured together in spaced relation and adapted to be secured to the underside of a header of a doorway,

a shaft rotatably supported in said plates and having a door supporting hinge pin projecting downwardly therefrom and non-rotatably engageable with the upper edge of a door,

equal and opposite bifurcated crank arms projecting from said shaft and angled equally toward said rod. between said plates,

follower rolls rotatably mounted between the bifurca tions on the ends of said arms,

a cam plate reciprocable along the axis of said rod between said plates,

means loosely connecting said rod to the adjacent inner end of said cam plate,

roller means on said cam plate and coacting guide slots formed in the inner sides of said mounting plates forming a relatively close longitudinal guiding engagement between the mounting plates and the inner end of the cam plate,

other roller means at the outer end of said cam plate engaged with said slots and forming a relatively loose longitudinal guiding engagement between the mounting plates and the outer end of said cam plate,

said cam plate defining a central opening having symmetrical cam edges alternately engageable with said follower rolls upon opposite swinging motion of said crank arms,

said cam edges extending from a point at the outer end of the opening in a laterally outward incline toward said shaft to a first hold open peak,

then along an opposite outward door retarding incline to a transversely extending edge generally perpendicular to said guide slots,

a laterally inwardly facing notch of a width to closely receive one of said follower rolls merging with the laterally outer end of said transversely extending edge and extending longitudinally inwardly therefrom,

said notch being deeper than the radius of said follower rolls by a distance approximately equal to the tolerance of the loose engagement of the outer end of the cam plate with said guide plates,

an axially inwardly extending and inclined edge at the inner end edge of said notch coacting with one follower roll to move said cam plate to the limit of said loose fit,

an axially inwardly facing auxiliary hold open peak spaced substantially inwardly from said last inclined edge,

said cam plate having holes formed therein selectively removably receiving a blocking pin at the inner side of said notches to block inward motion of said arms to block swinging motion of said arms in one direction,

and blocking pawls pivoted on said cam plate and selectively swingable into blocking relation to said auxiliary hold open peak.

2. In a door closer having a hydraulic cylinder with a spring pressed piston rod reciprocable therefnom, mechanism for operatively connecting sai-d rod to an oppositely swingable swinging door comprising,

a pair of mounting plates secured together in spaced :relation and adapted to be secured to the underside of a header of a doorway,

a shaft rotatably supported in said plates and having a door supporting hinge pin projecting therefrom and non-rotatably engageable with the edge of a door,

equal andopposite crank arms projecting from said shaft and angled equally toward said rod between said plates,

follower rolls rotatably mounted on the ends of said arms, v

a cam plate reciprocable along the axis of said rod between said plates,

means connecting said rod to the adjacent inner end of said cam plate,

means forming a relatively close longitudinal guiding engagement between the mounting plates and the inner end of the cam plate,

other means forming a relatively loose longitudinal guiding engagement between the mounting plates and the outer end of said cam plate,

said cam plate defining a central opening having symmetrical cam edges alternately engageable with said follower rolls upon opposite swinging motion of said crank arms,

said-cam edges extending from a point at the outer end of the opening in a laterally outwardincline toward said shaft to a first hold open peak,

then along an opposite outward door retarding incline to a transversely extending edge generally perpendicular to said guide slots,

a laterally inwardly facing notch of a width to closely receive one of said follower rolls merging with the laterally outer end of said transversely extending idge and extending longitudinally inwardly thererom,

said notch being deeper than the radius of said follower rolls by a distance approximately equal to the tolerance of the loose engagement of the outer end of the cam plate with said guide plates,

an axially inwardly extending and inclined edge at the inner end edge of said notch coacting with one follower roll to move said cam plate to the limit of said loose fit,

5 an axially inwardly facing auxiliary hold open peak spaced substantially inwardly from said last inclined edge,

said cam plate having holes formed therein selectively removably receiving a blocking pin at the inner side of said notches to block inward motion of said arms to block swinging motion of said arms in one direction,

and blocking pawls pivoted on said cam plate and selectively swingable into blocking relation to said auxiliary hold open peak.

3. In a two Way door closer having a hydraulic cylinder with a spring pressed piston rod reciprocable therefrom, mechanism for operatively connecting said rod to an oppositely swingable swinging door comprising,

a pair of mounting plates secured together in spaced relation and adapted to be secured to the underside of a header of a doorway,

a shaft rotatably supported in said plates and having a door supporting hinge pin projecting downwardly therefrom and non-rotatably engageable with the upper edge of a door,

equal and opposite bifurcated crank arms projecting from said shaft,

follower rolls rotatably mounted between the bifurcations on the ends of said arms,

a cam plate reciprocable along the axis of said rod between said plates,

means loosely connecting said rod to the adjacent inner end of said cam plate,

coacting guide means forming a relatively close longitudinal guiding engagement between the mounting plates and the inner end of the cam plate,

coacting guide means forming a relatively close longitudinal guiding engagement between the mounting plates and the inner end of the cam plate,

other means forming a relatively loose tolerance longitudinal guiding engagement between the mounting plates and the outer end of said cam plate,

said cam plate defining a central opening having symmetrical cam edges alternately engageable with said follower rolls upon opposite swinging motion of said crank arms,

said cam edges extending from a point at the outer end of the opening in a laterally outward incline toward said shaft to a first hold open peak,

then along an opposite outward door retarding incline to a transversely extending edge generally perpendicular to said guide slots,

a laterally inwardly facing notch of a width to closely receive one of said follower rolls merging with the laterally outer end of said transversely extending edge and extending longitudinally inwardly therefrom,

said notch being deeper than the radius of said follower rolls by a distance approximately equal to the tolerance of the loose engagement of the outer end of the cam plate with said guide plates,

an axially inwardly extending edge at the inner end edge of said notch coacting with one follower roll to move said cam plate to the limit of said loose fit,

an axially inwardly facing auxiliary door retarding edge and hold open peak spaced substantially inwardly from said last edge,

and blocking pawls pivoted on said cam plate and selectively swingable into blocking relation to said auxiliary hold open peak.

4. In a two way door closer having a hydraulic cylincler with a spring pressed piston rod reciprocable therefrom, mechanism for operatively connecting said rod to 75 an oppositely swingable swinging door comprising,

aoraeoe a shaft rotatably supported in said plates and having a l door supporting hinge pin projecting downwardly thereform and non-rotatably engageable with the upper edge of a door,

equal and opposite bifurcated crank arms projecting from said shaft,

follower rolls rotatably mounted between the bifurcations on the ends of said arms,

a cam plate reciprocable along the axis of said rod between said plates,

means loosely connecting said rod to the adjacent inner end of said cam plate,

coacting guide means forming a relatively close longitudinal guiding engagement between the mounting plates and the inner end of the cam plate,

coacting guide means forming a relatively close longitudinal guiding engagement between the mounting plates and the inner end of the cam plate,

other means forming a relatively loose tolerance longitudinal guiding engagement between the mounting plates and the outer end of said cam plate,

said cam plate defining a central opening having symmetrical carn edges alternately engageable with said follower rolls upon opposite swinging motion of said crank arms,

said cam edges extending from a point at the outer end'of the opening in a laterally outward incline toward said shaft to a first hold open peak,

then along an opposite outward door retarding incline to a transversely extending edge generally perpendicular to said guide slots,

at laterally inwardly facing notch of a width to closely receive one of said follower rolls merging with the laterally outer end of said transversely extending edge and extending longitudinally inwardly therefrom,

said notch being deeper than the radius of said follower rolls by a distance approximately equal to the tolerance of the loose engagement of the outer end of the cam plate with said guide plates,

an axially inwardly extending edge at the inner end edge of said notch coacting with one follower roll to move said cam plate to the limit of said loose fit,

and an axially inwardly facing auxiliary door retarding edge spaced substantially inwardly from said last edge.

5. In a door closer having a hydraulic cylinder with a spring pressed piston rod reciprocable therefrom, mechanism for operatively connecting said rod to a swingable swinging door comprising,

a pair of mounting plates secured together in spaced relation and adapted to be secured in the header of a doorway,

a shaft rotatably supported in said plates and having a door supporting hinge pin projecting therefrom and non-rotatably engageable with the edge of a door,

equal crank arms proiecting oppositely from said shaft and angled equally toward said rod between said plates,

follower rolls rotatably mounted on the ends of said arms,

a cam plate reciprocable along the axis of said rod between said plates,

means connecting said rod to the adjacent inner end of said cam plate,

means forming a relatively close longitudinal guiding engagement between the mounting plates and the inner end of the cam plate,

other means forming a relatively loose longitudinal guiding engagement between the mounting plates and the outer end of said cam plate,

said cam plate defining a central opening having cam edges engageable with said follower rolls upon swinging motion of said crank arms,

said cam edges extending from a point at the outer end of the opening in a laterally outward incline toward said shaft to a first hold open peak,

then along an opposite outward door retarding incline to a transversely extending edge generally perpendicular to said guide slots,

a laterally inwardly facing notch of a Width to closely receive one of said follower rolls merging with the laterally outer end of said transversely extending edge and extending longitudinally inwardly there from,

said notch being deeper than the radius of said follower rolls by a distance approximately equal to the tolerance of the loose engagement of the outer end of the cam plate with said guide plates,

an axially inwardly extending edge coacting with one follower roll to move said cam plate to the limit of said loose fit,

an axially inwardly facing auxiliary retarding edge and hold open peak spaced inwardly and oppositely from said last edge engageable with one of said rolls in the open position of the door,

and a blocking pawl pivoted on said cam plate and selectively swingable into blocking relation to said auxiliary hold open peak.

6. In a door closer having a hydraulic cylinder with a spring pressed piston rod rec-iprocab-le therefrom, mechanism for operatively connecting said rod to a swingable swinging door comprising,

a pair of mounting plates secured together in spaced relation and adapted to be secured in the header of a doorway,

a shaft rotatably supported in said plates and having a door supporting hinge pin projecting therefrom and non-rotatably engageable with the edge of a door,

crank arms projecting oppositely from said shaft,

follower rolls rotatably mounted on the ends of said arms,

a cam plate reciproca'ble along the axis of said rod between said plates,

means connecting said rod to the adjacent inner end of said cam plate,

means forming a guiding engagement between the mounting plates and the cam plate,

said cam plate defining a central opening having cam edges engageable with said follower rolls upon swinging motion of said crank arms,

said cam edges extending from a point at the outer end of the opening in a laterally outward incline toward said shaft to a first hold open peak,

then along an opposite outward door retarding incline to a transversely extending edge generally perpendicular to said guide slots,

a laterally inwardly facing notch of a width to closely receive one of said follower rolls merging with the laterally outer end of said transversely extending edge and extending longitudinally inwardly therefrom,

an axially inwardly facing auxiliary retarding edge and hold open peak spaced inwardly and oppositely from said last edge engageable with one of said rolls in the open position of the door.

7. Regulating cam mechanism for a door closer having a driving pin connectable to the edge of a door and a spring pressed, hydraulically retarded piston rod recipocable in a plane transverse to said pin comprising,

a pair of crank arms projecting oppositely from said pin in said plane and angled toward said rod,

cam roll followers on the ends of said arms,

a cam plate drivingly connected to said rod for reciprocation axially inwardly and outwardly along the axis of said rod,

aunt

symmetrical cam edges on said plate coacting with said followers and including spaced laterally inwardly facing locking notches receiving and embracing both sides of said follower rolls in the centered transversely extending positions of said arms,

transversely inwardly extending edges at the opposite edges of said notches from said rod merging at their inner ends with edges inclined toward said rod,

hold open peaks at the inner ends of said inclined edges,

axially extending edges at the inner ends of said notches each engageable with one of said followers to position the other follower in the opposite notch,

and guide means engageable with said cam plate guiding the plate generally axially to said rod and permitting limited transverse twisting of said cam plate to permit either of said followers to move singly transversely out of said notches when actuated by the opposite follower,

and spaced symmetrical edges disposed axially inwardly of said notches engageable alternatively with one of said followers when the other follower is engaged with said inclined edges to distribute the forces transmitted between said followers and said cam plate,

and auxiliary hold open peaks at the ends of last edges.

8. Regulating cam mechanism for a door closer having a driving pin connectable to the edge of a door and a spring pressed, hydraulically retarded piston rod reciproca ble in a plane transverse to said pin comprising,

a pair of crank arms projecting oppositely from said pin in said plane,

a pair of crank arms projecting oppositely from said pin in said plane,

cam roll followers on the ends of said arms,

a cam plate drivingly connected to said rod for reciprocation axially inwardly and outwardly along the axis of said rod,

symmetrical cam edges on said plate coacting with said followers and including spaced laterally inwardly facing locking notches receiving and embracing both sides of said follomer rolls in the centered transversely extending positions of said arms,

transversely inwardly extending edges at the opposite edges of said notches from said rod merging at their inner ends with edges inclined toward said rod,

hold open peaks at the inner ends of said inclined edges,

axially extending edges at the inner ends of said notches each engageable with one of said followers to position the other follower in the opposite notch,

and guide means engageable with said cam plate guiding the plate generally axially of said rod and permitting limited transverse twisting of said cam plate to permit either of said followers to move singly transversely out of said notches when actuated by the opposite follower,

and spaced symmetrical edges disposed axially inwardly of said notches engageable alternatively with one of said followers when the other follower is engaged with said inclined edges to distribute the forces transmitted between said followers and said cam plate.

9. Regulating cam mechanism for a door closer having a driving pin connectable to the edge of a door and a spring pressed, hydraulically retarded piston rod reciprocable in a plane transverse to said pin comprising,

a pair of crank arms projecting oppositely from said pin in said plane,

cam followers on the ends of said arms,

a cam plate drivingly connected to said rod for reciprocation axially inwardly and outwardly along the axis of said rod,

symmetrical cam edges on said plate coacting with said followers and including spaced laterally inwardly facing locking notches receiving and embracing both sides of said followers in the centered transversely extending positions of said arms,

transversely inwardly extending edges at the opposite edges of said notches from said rod merging at their inner ends with edges inclined toward said rod, hold open peaks at the inner ends of said inclined edges,

axially extending edges at the inner ends of said notches each engageable with one of said followers to position the other follower in the opposite notch,

guide means engageable with said cam plate guiding the plate generally axially of said rod and permitting limited transverse twisting of said cam plate to permit either of said followers to move singly transversely of said notches when actuated by the opposite follower,

and spaced symmetrical edges disposed axially inwardly of said notches engageable alternatively with one of said followers when the other follower is engaged with said inclined edges to distribute the forces transmitted between said followers and said cam plate,

and auxiliary hold open peaks at the ends of last edges.

10. Regulating cam mechanism for a door closer having a driving pin connectable to the edge of a door and a spring pressed, hydraulically retarded piston rod reciprocable in a plane transverse to said pin comprising,

a pair of crank arms projecting oppositely from said pin in said plane,

cam followers on the ends of said arms,

a cam plate drivingly connected to said rod for reciprocation axially inwardly and outwardly along the axis of said rod,

symmetrical cam edges on said plate coacting with said followers and including spaced laterally inwardly facing locking notches receiving and embracing both sides of said followers in the centered transversely extending positions of said arms,

transversely inwardly extending edges at the opposite edges of said notches from said rod merging at their inner ends with edges inclined toward said rod,

axially extending edges at the inner ends of said notches each engageable with one of said followers to position the other follower in the opposite notch,

guide means engageable with said cam plate guiding the plate generally axially of said rod and permitting limited transverse twisting of said cam plate to permit either of said followers to move singly transversely of said notches when actuated by the opposite follower,

and spaced symmetrical edges disposed axially inwardly of said notches engageable alternatively with one of said followers when the other follower is engaged with said inclined edges to distribute the forces transmitted between said followers and said cam plate,

and hold open peaks at the ends of last edges.

11. Regulating cam mechanism for a door closer having a driving pin connectable to the edge of a door and a spring pressed, hydraulically retarded piston rod reciprocable in a plane transverse to said pin comprising,

a pair of crank arms projecting oppositely from said cam followers on the ends of said arms,

a cam plate drivingly connected to said rod for reciprocation axially inwardly and outwardly along the axis of said rod,

symmetrical cam edges on said plate coacting with said followers and including spaced laterally inwardly facing locking notches receiving and embracing both sides of said followers in the centered transversely extending positions of said arms,

transversely inwardly extending edges at the opposite edges of said notches from said rod merging at their inner ends with edges inclined toward said rod,

hold open peaks at the inner ends of said inclined edges,

axially extending edges at the inner ends of said notches each engageable with one of said followers to position the other follower in the opposite notch,

1 1 and guide means engageabie with said cam plate guiding the plate generally axially of said rod and permitting limiied transverse twisting of said cam plate to permit either of said followers to move singly transversely out of said notches when actuated by the 0pposite follower.

UNITED STATES PATENTS 

11. REGULATING CAM MECHANISM FOR A DOOR CLOSER HAVING A DRIVING PIN CONNECTABLE TO THE EDGE OF A DOOR AND A SPRING PRESSED, HYDRAULICALLY RETARDED PISTON ROD RECIPROCABLE IN A PLANE TRANSVERSE TO SAID PIN COMPRISING, A PAIR OF CRANK ARMS PROJECTING OPPOSITELY FROM SAID PIN, CAM FOLLOWERS ON THE ENDS OF SAID ARMS, A CAM PLATE DRIVINGLY CONNECTED TO SAID ROD FOR RECIPROCATION AXIALLY INWARDLY AND OUTWARDLY ALONG THE AXIS OF SAID ROD, SYMMETRICAL CAM EDGES ON SAID PLATE COACTING WITH SAID FOLLOWERS AND INCLUDING SPACED LATERALLY INWARDLY FACING LOCKING NOTCHES RECEIVING AND EMBRACING BOTH SIDES OF SAID FOLLOWERS IN THE CENTERED TRANSVERSELY EXTENDING POSITIONS OF SAID ARMS, TRANSVERSELY INWARDLY EXTENDING EDGES AT THE OPPOSITE EDGES OF SAID NOTCHES FROM SAID ROD MERGING AT THEIR INNER ENDS WITH EDGES INCLINED TOWARD SAID ROD, HOLD OPEN PEAKS AT THE INNER ENDS OF SAID INCLINED EDGES, AXIALLY EXTENDING EDGES AT THE INNER ENDS OF SAID NOTCHES EACH ENGAGEABLE WITH ONE OF SAID FOLLOWERS TO POSITION THE OTHER FOLLOWER IN THE OPPOSITE NOTCH, AND GUIDE MEANS ENGAGEABLE WITH SAID CAM PLATE GUIDING THE PLATE GENERALLY AXIALLY OF SAID ROD AND PERMITTING LIMITED TRANSVERSE TWISTING OF SAID CAM PLATE TO PERMIT EITHER OF SAID FOLLOWERS TO MOVE SINGLY TRANSVERSELY OUT OF SAID NOTCHES WHEN ACTUATED BY THE OPPOSITE FOLLOWER. 